This invention relates to semi-automatic rifles, and more particularly to a self-unlocking device for separation of the bolt carrier from the barrel in a semi-automatic rifle during recoil.
In the "Anti-Armor Gun" disclosed in my prior U.S. Pat. No. 4,677,897, issued July 7, 1987, a recoiling barrel is provided for carrying rearward the bolt carrier and the bolt, while still locked to the barrel, in order to absorb the energy of recoil after the gun is fired. The front of the bolt is provided with radially projecting bolt lugs which are adapted to engage the locking lugs in the rear end of the barrel in order to lock the bolt within the barrel in battery and firing positions. The barrel is also provided with an abutment member which engages a barrel travel stop fixed within the housing to stop the rearward movement of the barrel. When the barrel stops, the bolt carrier and bolt continue their rearward travel simultaneously rotating the bolt to unlock the bolt lugs from the barrel to completely separate the bolt carrier from the barrel. The barrel springs then return the barrel to its original forward position.
In the gun disclosed in U.S. Pat. No 4,677,897, the rearward movement of the recoiling barrel is always stopped abruptly, placing substantial stress upon the interlocking lugs of the bolt and the barrel. Moreover, the sudden impact and stopping of the recoiling barrel is transmitted in the form of a "kick" to the shoulder of the operator of the weapon.
Furthermore, the extractor mechanism is subjected to a substantial degree of shock and fatigue upon the abrupt stopping of the barrel and the sudden commencement of the extraction of the cartridge.